Solar battery module for optical electrolysis device and optical electrolysis device

ABSTRACT

Partition member  34  is provided, which partitions the interior of glass container  31  into reduction reaction chamber  32  and oxidation reaction chamber  33  and which is made of a polymer electrolyte that conducts hydrogen ions; solar battery modules  35  are mounted on this partition member  34 , for example in a matrix arrangement of five rows and three columns; a solar battery module  35  has a photocell array (photoelectromotive force: 2.0-2.4 V) consisting of four spherical solar battery elements (photoelectromotive force: 0.5-0.6 V) connected in series, anode  46 , and cathode  48 ; solar battery modules  35  are mounted on partition member  34  so that anode  46  is in contact with the electrolyte of oxidation reaction chamber  33  and cathode  48  is in contact with the electrolyte of reduction reaction chamber  32 ; sunlight is shined on solar battery modules  35 , and the photoelectromotive force electrolyzes the water and produces hydrogen gas from cathode  48  and oxygen gas from anode  46.

TECHNICAL FIELD

This invention concerns a solar battery module for a photoelectrolyticdevice and a photoelectrolytic device that employs the solar batterymodule; in particular, it concerns technology in which the electrolysisof an electrolyte is carried out by solar energy using a solar batterymodule in which multiple spherical solar battery elements are connectedin series and that generates the required electrolysis voltage.

BACKGROUND TECHNOLOGY

Heretofore there have been attempts in which water is electrolyzed bythe photoelectromotive force produced by titanium oxide (TiO₂), butbecause the wavelength of the light that allows energy conversion withtitanium oxide is about 420 nm or less, the energy conversion efficiencywith respect to sunlight is very low, and this technology has not beenput to practical use. Heretofore, technology to electrolyze anelectrolyte with the photoelectromotive force of sunlight by means of asolar battery immersed in the electrolyte has appeared in U.S. Pat. No.4,021,323 and in unexamined patent application publication H6-125210[1994] relating to the present applicant.

The U.S. patent discloses a solar battery array in which a pn junctionis formed on spherical crystals of silicon and a common metal electrodefilm is formed on these multiple spherical crystals (a microphotoelectric cell), and a photochemical energy conversion device isdescribed in which such an array of solar batteries is immersed in anelectrolyte, and a solution of hydriodic acid or hydrobromic acidelectrolyzed by the photoelectromotive force of sunlight.

Unexamined patent application publication H6-125210 [1994] discloses anarray of light receiving elements in which multiple spherical crystalsare formed near the surface of a semiconductor crystal substrate inmatrix form and integral with the semiconductor crystal substrate, aphotoelectromotive force generation part including pn junctions isformed on the surface part of the spherical crystals, and individualfront-surface electrodes and a common back-surface electrode are formedon these multiple spherical crystals; it also discloses aphotoelectrolytic device that includes the array of light receivingelements.

But with the technology described in these two documents, the directionin which sunlight can be received is limited to one surface, making itdifficult to increase the light utilization rate in making use of thelight in a light space.

In forming a solar battery array and individually forming the electrodefilms on the array of light receiving elements, the size of thephotoelectromotive force is determined by the number of serial junctionsof spherical crystals on which a pn junction is formed, so the solarbattery array and array of light receiving elements must be designed andfabricated for each photoelectrolytic device. This makes it difficult toreduce the cost of fabricating solar battery arrays and arrays of lightreceiving elements suitable for photoelectrolytic devices, and makes itdifficult to fabricate solar battery arrays and arrays of lightreceiving elements of wide application suitable for photoelectrolyticdevices of various types and sizes.

The inventor of this invention has done research on photoelectrolyticdevices that employ spherical semiconductor devices (of diameter about0.5-2.0 mm) that function as micro photoelectric cells (or microphotocatalysts). In a photoelectrolytic device of this kind, it isnecessary to support many small-particle spherical semiconductor devicesin an electrolyte arranged so they can receive light, and to surelyseparate the reaction products, but as yet no structure has beenproposed for thus arranging and supporting a large number of sphericalsemiconductor devices.

The purpose of this invention is to provide a solar battery module for aphotoelectrolytic device that makes use of multiple independentgrain-shaped spherical solar battery elements. A further purpose of thisinvention is to provide a solar battery module for a photoelectrolyticdevice in which one can appropriately set the size of thephotoelectromotive force. Another purpose of this invention is toprovide a solar battery module for a photoelectrolytic device ofsuperior generality that can be applied to various photoelectrolyticdevices. Another purpose of this invention is to provide a solar batterymodule for a photoelectrolytic device that can receive sunlight fromvarious directions.

Another purpose of this invention is to provide a solar battery modulefor a photoelectrolytic device that can prevent overvoltage at theelectrolysis electrodes and can promote the separation of reactionproducts from the electrodes. Another purpose of this invention is toprovide a solar battery module for a photoelectrolytic device that haselectrolysis electrodes having a catalytic function. Another purpose ofthis invention is to provide a photoelectrolytic device in which thesolar battery module for a photoelectrolytic device is applied.

DISCLOSURE OF THE INVENTION

The solar battery module for a photoelectrolytic device of thisinvention is characterized in that it has multiple spherical solarbattery elements, a transparent cylindrical holding member thataccommodates and holds these spherical solar battery elements in acondition where they are electrically connected in series, and a pair ofelectrolysis electrodes that are mounted liquid-tightly on both ends ofthis holding member and are exposed to the outside of the holdingmember; each of the spherical solar battery elements has a p-type orn-type spherical semiconductor crystal, a photoelectromotive forcegeneration part that includes a pn junction formed on the surface partof this spherical semiconductor crystal, and a pair of electrodes formedon both ends that is symmetrical about the center of the sphericalsemiconductor crystal in order to tap the photoelectromotive force thatis generated by this photoelectromotive force generation part, and in astate in which it is immersed in an electrolyte, it is suitable forelectrolysis of the electrolyte by the photoelectromotive force causedby sunlight.

Here, it is desirable to set the number of the multiple spherical solarbattery elements in accordance with the voltage of thephotoelectromotive force to be generated by the photoelectromotive forcegeneration part and the electrolysis voltage needed for the electrolyte.On each surface of the pair of electrolysis electrodes it is desirableto form a metal form that has a catalytic function that promoteselectrolytic reactions. And it is desirable to form on the part of theelectrolysis electrodes that comes into contact with the electrolyte apointy tip in order to reduce the overvoltage and promote the separationof reaction products.

In the solar battery module for a photoelectrolytic device, multiplespherical solar battery elements are accommodated in a transparentholding member in a state in which they are connected electrically inseries, so a photoelectromotive force is generated by light that isincident from various directions. The size of the photoelectromotiveforce can be set freely by varying the number of series-connectedspherical solar battery elements, which provides superior generalitythat can be applied to various photoelectrolytic devices. By forming ametal film that has a catalytic function on the surface of theelectrolysis electrodes, the electrolysis can be speeded up by thecatalytic effect. And by forming a pointy tip on the electrolysiselectrodes, overvoltage can be reduced and the separation of reactionproducts can be promoted.

The photoelectrolytic device of this invention is characterized in thatit has a container that accommodates an electrolyte inside it and intowhich sunlight can be introduced; multiple solar battery modules thatare arranged in a state in which they are immersed in an electrolyteinside this container, receive sunlight, and generate photoelectromotiveforce; and a partition member that partitions the space between theelectrolysis anode and the electrolysis cathode of these solar batterymodules to make it possible to separate the reaction products producedat both electrodes, and on which multiple solar battery modules arepiercingly mounted.

Here, it is desirable that each solar battery module have multiplespherical solar battery elements that each have a p-type or n-typespherical semiconductor crystal, a photoelectromotive force generationpart that includes a pn junction formed on the surface part of thisspherical semiconductor crystal, and a pair of electrodes formed on bothends that is symmetrical about the center of the spherical semiconductorcrystal in order to tap the photoelectromotive force that is generatedby this photoelectromotive force generation part; a transparentcylindrical holding member that accommodates and holds these sphericalsolar battery elements in a condition where they are electricallyconnected in series; and an electrolysis anode and electrolysis cathodethat are mounted liquid-tightly on both ends of this holding member andare exposed in the electrolyte. It is also desirable that thecomposition be such that sunlight can shine into the container at leastfrom above. Also, the partition member may consist of a solid polymerelectrolyte, and if so, the polymer electrolyte may be a hydrogen ionconductor.

When sunlight shines onto this photoelectrolytic device, aphotoelectromotive force is generated in the multiple solar batterymodules, oxidation reactions occur at the electrolysis anode of eachsolar battery module, and reduction reactions occur at the electrolysiscathode. Because a partition member is provided that forms a partitionbetween the anode and cathode to make it possible to separate thereaction products that are produced at both electrodes, the oxidationreaction products and the reduction reaction products can be removed tothe outside while remaining separated by the partition member. Moreover,multiple solar battery modules are mounted piercingly on this partitionmember, simplifying the composition for mounting and supporting multiplesolar battery modules.

Each solar battery module of this photoelectrolytic device performsitself the same effects as the aforesaid solar battery module for aphotoelectrolytic device. If the partition member consists of a polymerelectrolyte, ions will permeate through the partition member, so ionscan be allowed to migrate while maintaining the function of keeping thereaction products isolated from each other. For example, if it isnecessary to allow the hydrogen ions produced by electrolysis topermeate through, the partition member may be made of a hydrogenion-conducting polymer electrolyte.

According to an embodiment of the invention, there is provided a solarbattery module for a photoelectrolytic device comprising: a cylindricalholding member into which light can be introduced; the cylindricalholding member has a first end and a second end; a plurality of solarbattery elements contained within the cylindrical holding member; atleast some of the plurality of solar battery elements are connected witheach other; a first electrolysis electrode; the first electrolysiselectrode is electrically connected to a first outer solar batteryelement and the first end with a first seal; the first seal isliquid-tight; a second electrolysis electrode; the second electrolysiselectrode is electrically connected to an opposite second outer solarbattery element and the second end with a second seal; the second sealis liquid-tight; and the cylindrical holding member holding theplurality of solar battery elements in a cylindrical array which can beilluminated from any radial direction.

According to another embodiment of the invention, there is provided aphotoelectrolytic device comprising: a container into which light can beintroduced; at least one partition member; the at least one partitionmember partitioning the container into at least two distinct fluidisolated areas; a plurality of solar battery modules piercingly attachedto the at least one partition member; the at least one partition memberhas a first surface and a second surface; an electrolyte substantiallyfilling the container; each of the plurality of solar battery moduleshas an anode end and a cathode end; the cathode end is exposed to theelectrolyte between the container and the first surface; the anode endis exposed to the electrolyte between the container and the secondsurface; a first means for circulating the electrolyte between thecontainer and the first surface to replenish the electrolyte as theelectrolyte is electrolyzed; a second means for circulating theelectrolyte between the container and the second surface to replenishthe electrolyte as the electrolyte is electrolyzed; a first collectingmeans for collecting electrolysis products created at the anode end; anda second collecting means for collecting electrolysis products createdat the cathode end. dr

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross-sectional view of the photoelectrolyticdevice of example 1;

FIG. 2 is a cross-sectional view of FIG. 1 along line II—II;

FIG. 3 is a cross-sectional view of a spherical solar battery element;

FIG. 4 is an enlarged cross-sectional view of a solar battery module ofa photoelectrolytic device;

FIG. 5 is a vertical cross-sectional view of the photoelectrolyticdevice of example 2;

FIG. 6 is a cross-sectional view of FIG. 5 along line VI—VI;

FIG. 7 is an enlarged cross-sectional view of a solar battery module ofthe photoelectrolytic device of FIG. 5; and

FIG. 8 is an exploded perspective view of the photoelectrolytic deviceof example 3.

PREFERRED EMBODIMENTS OF THE INVENTION

The following is a description of examples of this invention, in whichreference is made to the drawings.

Example 1 (see FIGS. 1-3)

Photoelectrolytic device 1 in this example is a device thatelectrolyzes, by the photoelectromotive force produced by solar energy,an electrolytic solution of water and carbon dioxide gas, producingmethane gas (CH₄) and oxygen gas (O₂).

As shown in FIGS. 1 and 2, this photoelectrolytic device 1 has acontainer 2 of circular cross-section that accommodates the electrolyte,a cylindrical partition member 3 provided in the center of thiscontainer 2, multiple solar battery modules 10 mounted on this partitionmember 3 and piercing it radially, first supply port 4 for supplyingwater and second supply port 5 for supplying carbon dioxide gas formedon the base wall part 2 a of container 2, and first lead-out port 6 fortaking out the methane gas and second lead-out port 7 for taking out theoxygen gas, each formed in pipe shape integrally with cover part 2 c ofcontainer 2.

The container 2 has base wall part 2 a, which is made of stainless steelor another metal, cylindrical wall part 2 b, which is made oftransparent glass, fits into the upper part of this base wall part 2 a,and is secured by an inorganic adhesive, and cover part 2 c, which ismade of glass, fits into the upper part of this cylindrical wall part 2b, and covers it in a way that can be opened and closed; first andsecond supply ports 4 and 5 are formed on base wall part 2 a, and firstand second lead-out parts 6 and 7 are formed on cover part 2 c.

The cylindrical partition member 3 consists of a hydrogen ion-conductingpolymer electrolyte (for example, fluorine sulfonate), and the lowerpart of partition member 3 fits liquid-tightly around boss 2 d of basewall part 2 a. For mounting solar battery modules 10, partition member 3consists of two split parts 3 a and 3 b that adhere on joining surface 3c on a vertical plane through the center. Also, partition member 3 canconsist of an integral item if the length of a solar battery module 10is formed smaller than the inside diameter of partition member 3.

The interior of partition member 3 is reduction reaction chamber 8, andthe space between cylindrical wall part 2 b and partition member 3 isoxidation reaction chamber 9; electrolysis cathode 14 of solar batterymodule 10 is in contact with the electrolyte in reduction reactionchamber 8, and electrolysis anode 13 of solar battery module 10 is incontact with the electrolyte in oxidation reaction chamber 9.

The first supply port 4 is connected to oxidation reaction chamber 9through opening hole 2 e in base wall part 2 a, and second supply port 5is connected to reduction reaction chamber 8 through opening hole 2 f inboss 2 d. First lead-out port 6 is connected to the upper end ofreduction reaction chamber 8, and second lead-out port 7 is connected tothe upper end of oxidation reaction chamber 9.

As shown in FIGS. 1 and 2, in the case of this example, a total of 18solar battery modules 10 are provided, and in the view from the topthese solar battery modules 10 are arranged around the circumferencespaced, for example, 60<deg> apart, and the electrolysis cathodes 14 ofthe solar battery modules 10 are arranged at 18 different levels in thevertical direction in order to keep the cathodes as far apart from eachother as possible.

As shown in FIGS. 3 and 4, a solar battery module 10 has four sphericalsolar battery elements 11 whose diameter is, for example, 0.5-2.0 mm,holding member 12, which consists of a transparent quartz glass tubethat accommodates and holds these solar battery elements 11 in a statein which they are electrically connected in series, and electrolysisanode 13 (the oxidation electrode) and electrolysis cathode 14 (thereduction electrode), which are mounted liquid-tightly on both ends ofthis holding member 12 and are exposed to the outside of holding member12.

As shown in FIG. 3, a spherical solar battery element 11 (microphotoelectric cell) has spherical p-type silicon single crystal 15, n+diffusion layer 16 formed by heat-diffusing phosphorus (P) onto much ofits spherical surface, pn+ junction 17 of roughly spherical surfaceshape, negative electrode 18 and positive electrode 19 formed on bothends symmetrically about the center of p-type silicon single crystal 15,and anti-reflective coating 20, and formed on this spherical solarbattery element 11 is a photoelectromotive force generation part thatincludes pn+ junction 17 (photoelectromotive force: 0.5-0.6 V). Thephosphorus concentration of the n+ diffusion layer 16 is about 2×10²⁰cc⁻¹, and pn+ junction 17 is formed in a position at a depth of about0.5-1.0 μm from the spherical surface. Positive electrode 19 iselectrically connected to the surface of p-type silicon single crystal15, and negative electrode 18 is electrically connected to the surfaceof n+ diffusion layer 16. Positive electrode 19 is an ohmic contacthaving a thickness of, for example, 1.0 μm that consists of a vapordeposition film of titanium (Ti) and a vapor deposition film of nickel(Ni) on its outside surface, and negative electrode 18 is an ohmiccontact of similar composition.

Reflection prevention film 20 is formed on the entire surface other thanthe surface of negative electrode 18 and positive electrode 19, and thisreflection prevention film 20 consists of a SiO₂ coating (for example,thickness: 0.3-0.7 μm) and, on its surface, a TiO₂ coating (for example,thickness: 0.3-1.0 μm).

If spherical solar battery elements 11 are to be fabricated, a sphericalsolar battery element 11 can be fabricated by, for example, using anelectromagnetic floating heating device at the top of a verticaldropping tube to melt p-type silicon grains as they float, allowing themelt to solidify as it falls through the vacuum of the dropping tube,thereby making spherical p-type silicon single crystals, and applying tothese spherical p-type silicon single crystals various well knownprocessing applied in semiconductor integrated circuit manufacturingtechnology and various similar processing.

As shown in FIG. 4, four spherical solar battery elements 11 areaccommodated inside holding member 12 as a series-connected solarbattery array 12 (photoelectromotive force: 2.0-2.4 V), electrolysisanode 13 is electrically connected to positive electrode 19 of solarbattery array 21, and electrolysis cathode 14 is electrically connectedto negative electrode 18 of solar battery array 21. Anode 13 consists ofanode main body 13 a, which consists of nickel (Ni), iron (Fe), or analloy of them, and platinum (Pt) coating 13 b, which is plated onto itsoutside surface and has a catalytic function, and cathode 14 consists ofcathode main body 14 a, which consists of nickel (Ni), iron (Fe), or analloy of them, and copper (Cu) or copper-alloy coating 14 b, which isplated onto its outside surface and has a catalytic function. Anode mainbody 13 a of anode 13 is inserted into holding member 12, is fused withglass, and has a liquid-tight structure, and on the end of anode 13 isformed a pointy tip 13 c for reducing the overvoltage and promoting theseparation of reaction products.

Cathode main body 14 a of cathode 14 is inserted into holding member 12,is fused with glass, and has a liquid-tight structure, and on the end ofcathode 14 is formed sideward-facing T-shaped stopping part 14 d, whilein the middle part of stopping part 14 d is formed a pointy tip 14 c forreducing the overvoltage and promoting the separation of reactionproducts. The width of stopping part 14 d is roughly the same as theoutside diameter of holding member 12, and the height of stopping part14 d is greater than the outside diameter of holding member 12.

Before gluing together the pair of two split parts 3 a and 3 b ofpartition member 3, a ring-shaped spacer 22 made of an insulatingmaterial is put inside the through-holes of each of the two split parts3 a and 3 b, solar battery module 10 is mounted by putting it throughspacer 22 and the through-hole from the inside, then putting the twosplit parts 3 a and 3 b together and gluing them on surface 3 c.

Next, we describe the operation of the above photoelectrolytic device 1.

When sunlight shines on this photoelectrolytic device 1 from above, forexample as shown by arrows A, or as shown by arrows B, or from variousother directions, a photoelectromotive force of about 0.5-0.6 V isgenerated by the photoelectromotive force generation part of eachspherical solar battery element 11 of solar battery module 10. Inspherical solar battery element 11, pn+ junctions 17 are formed overmuch of the surface of spherical p-type silicon single crystal 15, so itabsorbs the incident light of wavelength 400-1000 nm that enters thephotoelectromotive force generation part, efficiently converting thelight to electricity; not only the directly incident sunlight, but alsolight reflected from the base or other surfaces of container 2 and lightthat is repeatedly reflected and dispersed within container 2 isefficiently absorbed and converted to electricity. In solar batteryarray 21, four spherical solar battery elements 11 are connected inseries, so photoelectromotive force of about 2.0-2.4 V is generated bysolar battery array 21 and appears at cathode 14 and anode 13.

In oxidation reaction chamber 9, the water is decomposed into hydrogenions (H+) and oxygen ions (O−) on the surface of anode 13, and theoxygen ions are oxidized, producing oxygen gas (O₂). The hydrogen ions(H+) permeate through partition member 3, which is made of a polymerelectrolyte that conducts hydrogen ions, and migrate into reductionreaction chamber 8, where reduction reactions between carbon dioxide gas(CO₂) and hydrogen ions (H+) take place on the surface of cathode 14,producing methane gas (CH₄). The oxygen gas that is produced inoxidation reaction chamber 9 is led out through second lead-out port 7to an outside gas path not shown in the diagram, and the methane gasthat is produced in reduction reaction chamber 8 is led out throughfirst lead-out port 6 to an outside gas path not shown in the diagram.

In this solar battery module 10, the size of the photoelectromotiveforce can be varied by varying the number of series connections ofspherical solar battery elements 11, which is advantageous for applyingit to various kinds of photoelectrolytic devices. Holding member 12 istransparent, and spherical solar battery element 11 absorbs incidentlight from almost all directions, which is advantageous for thephotoelectric conversion of light whose direction of incidence changes,such as sunlight. The formation of pointy tips 13 c and 14 c on anode 13and cathode 14 can reduce overvoltage, promote the separation ofreaction products, and promote electrolysis reactions. The formation ofcoatings 13 b and 14 b, which have a catalytic function, on the surfaceof anode 13 and cathode 14 can promote oxidation reactions and reductionreactions.

In the photoelectrolytic device 1, cylindrical wall part 2 b and coverpart 2 c of container 2 are made of transparent glass, allowing lightfrom various directions to enter solar battery module 10. Oxidationreaction chamber 9 and reduction reaction chamber 8 are partitioned fromeach other by partition member 3, which is made of a hydrogenion-conducting polymer electrolyte, and solar battery modules 10 aremounted on this partition member 3, so the structure ofphotoelectrolytic device 1 is made simple by the fact that partitionmember 3 performs three functions: the function of separating reactionproducts (oxygen gas and methane gas), the function of allowing hydrogenions to permeate through, and the function of supporting multiple solarbattery modules 10. Also, this photoelectrolytic device 1 has is acomposition in which photoelectromotive force is generated by multiplesolar battery modules 10, which of course enhances the operation andeffect of the solar battery modules 10.

The example has been described by taking as an example photoelectrolyticdevice 1, which produces methane gas and oxygen gas from water andcarbon dioxide gas by the photoelectromotive force generated by solarenergy, but besides this, it is also possible to electrolytically reducecarbon dioxide gas and produce ethylene (CH₂═CH₂), methanol (CH₃OH),ethanol (C₂H₅OH), formic acid (HCOOH), oxalic acid (COOH)₂, etc. In thiscase, it is desirable to appropriately set the size of thephotoelectromotive force of solar battery array 21 by appropriatelysetting the number of series connections of spherical solar batteryelements 11 in solar battery module 10, and to make cathode 14, or itscoating 14 b that has a catalytic function, from copper or a copperalloy.

Example 2 (see FIGS. 5-7)

Photoelectrolytic device 30 in this example is a device that produceshydrogen gas (H₂) and oxygen gas (O₂) by electrolyzing water as theelectrolyte, powered by the photoelectromotive force generated by solarenergy.

As shown in FIGS. 5 and 6, this photoelectrolytic device 30 hascontainer 31, which has a circular cross-section, partition member 34,which partitions its interior into reduction reaction chamber 32 andoxidation reaction chamber 33, and, for example, 15 solar batterymodules 35, which are mounted piercingly on this partition member 34.This container 31 has base wall 31 a, cylindrical wall part 31 b, whichis integral with this base wall 31 a, and cover plate 31 c, which coversthe upper end of this cylindrical wall part 31 b so that it can beopened and closed. Fixed in mutually facing positions on the insidesurface of cylindrical wall part 31 b are guide members 36, which aremade of quartz glass or stainless steel and in which are formed verticalgrooves 36 a. Formed on the lower part of cylindrical wall part 31 b isone water supply port 37, and connected to this water supply port 37 iswater supply pipe 38. Formed on the upper part of cylindrical wall part31 b are first lead-out port 39 for guiding out the oxygen gas from theupper end of oxidation reaction chamber 33 and second lead-out port 40for guiding out the hydrogen gas from the upper end of reductionreaction chamber 32.

Like partition member 3 of the above example, partition member 34 isformed in the shape of a thin plate by a polymer electrolyte thatconducts hydrogen ions; it is mounted slidably in grooves 36 a in thepair of guide members 36, and formed near the lower end of partitionmember 34 is opening hole 34 a to allow the water to flow through.

The 15 solar battery modules 35 are arranged in a matrix of five rowsand three columns in a mode that pierces partition member 34,electrolysis cathodes 48 of these solar battery modules 35 are providedso as to make contact with the electrolyte inside reduction reactionchamber 32, and electrolysis anodes 46 are provided so as to makecontact with the electrolyte inside oxidation reaction chamber 33.

As shown in FIG. 7, solar battery module 35 has solar battery array 43,which consists of relay conductor 41 in the middle and four sphericalsolar battery elements 42 connected in series via this relay conductor41; holding member 44, which consists of a quartz glass tube thataccommodates this solar battery array 43 in series-connected condition;electrolysis anode 46, which is electrically connected to positiveelectrode 45 of solar battery array 43; and electrolysis cathode 48,which is electrically connected to negative electrode 47 of solarbattery array 43.

Spherical solar battery element 42 has the same structure and functionsas spherical solar battery element 11 of the above example, so adescription of it is omitted. The photoelectromotive force of sphericalsolar battery element 42 is 0.5-0.6 V, so the photoelectromotive forceof solar battery array 43 is 2.0-2.4 V. Anode 46 consists of anode mainbody 46 a, which is made of an iron-nickel alloy, and platinum coating46 b, which is on the surface of its tip and has a catalytic function,and on the end of anode 46 is formed a pointy tip 46 c for reducing theovervoltage and promoting the separation of reaction products. Cathode48, which has the same shape as anode 46, consists of cathode main body48 a, which is made of an iron-nickel alloy, and iridium (Ir) oriridium-alloy coating 48 b, which is on the surface of its tip and has acatalytic function, and on the end of cathode 48 is formed a pointy tip48 c for reducing the overvoltage and promoting the separation ofreaction products. Relay conductor 41 is also made of an iron-nickelalloy.

As shown in FIGS. 5 and 6, each solar battery module 35 goes through athrough-hole formed in partition member 34 and is mounted so that itsmiddle part in the longitudinal direction is positioned at the positionof partition member 34, with anode 46 exposed to oxidation reactionchamber 33 and cathode 48 exposed to reduction reaction chamber 32.

We describe the operation of this photoelectric device 30.

When sunlight shines on this photoelectrolytic device 30 from above, forexample as shown by arrows C, or as shown by arrows D, or from variousother directions, a photoelectromotive force of about 0.5-0.6 V isgenerated by the photoelectromotive force generation part of eachspherical solar battery element 42 of solar battery module 35 andappears at anode 46 and cathode 48. In oxidation reaction chamber 33,the water is decomposed into hydrogen ions (H+) and oxygen ions (O−) onthe surface of anode 46, and the oxygen ions are oxidized, producingoxygen gas (O₂). The hydrogen ions (H+) permeate through partitionmember 34, which is made of a polymer electrolyte that conducts hydrogenions, and migrate into reduction reaction chamber 32, where reductionreactions of the hydrogen ions (H+) take place, producing hydrogen gas(H₂). The oxygen gas that is produced in oxidation reaction chamber 33is led out through first lead-out port 39 to an outside gas path notshown in the diagram, and the hydrogen gas that is produced in reductionreaction chamber 32 is led out through second lead-out port 40 to anoutside gas path not shown in the diagram.

A solar battery module 35 of this photoelectrolytic device 30, besideshaving the same operation and effect as solar battery module 10 ofaforesaid model 1, has relay conductor 41 built into it in the middle ofholding member 44 in its longitudinal direction, which is advantageousfor increasing the strength and rigidity of holding member 44, and isalso advantageous for mounting solar battery module 35 on partitionmember 34. Also, the number of series connections of spherical solarbattery elements 42 can be changed by changing the length of relayconductor 41. However, relay conductor 41 is not mandatory and may beomitted. In this photoelectrolytic device 30, partition member 34 ismounted detachably via grooves 36 a in the pair of guide members 36,making it possible to remove solar battery modules 35 together withpartition member 34, which is advantageous for the maintenance of solarbattery modules 35.

Example 3 (see FIG. 8)

As in the above example 2, photoelectrolytic device 50 in this exampleis a device that produces hydrogen gas (H₂) and oxygen gas (O₂) byelectrolyzing water as the electrolyte, powered by thephotoelectromotive force generated by solar energy.

As shown in FIG. 8, this photoelectrolytic device 50 has box-shapedcontainer 51, which is made of, for example, sheet stainless steel;cover plate 52, which is made of transparent glass and covers the upperend of container 51 so that it can be opened and closed; five partitionplates 54 (partition members) that partition the interior of container51 into six reaction chambers 53 a and 53 b; for example, 21 solarbattery modules 55 mounted in each partition plate 54; water supply tube59; oxygen gas lead-out tube 57; and hydrogen gas lead-out tube 58. Onthe inside surface of the side walls at the front and back of container51 are glass or stainless-steel guide members 56 for mounting partitionplates 54, and five pairs of guide members 56, which are similar to theguide members 36 of above example 2, are secured opposite each other infive places where the partition plates 54 are mounted. Each partitionplate 54 is removably mounted by being air-tightly fitted into thegrooves in one pair of guide members 56. Flange 51 a is formedintegrally on the upper rim of container 51. Seal material correspondingto flange 51 a and seal material corresponding to the five partitionplates 54 are secured by adhesion to the undersurface of cover plate 52,cover plate 52 is placed onto the upper rim of container 51, and coverplate 52 is fixed releasably to flange 51 a by means of clamps andmultiple screws not shown in the diagram.

Notch 54 a for allowing water to pass through is formed on the frontedge of the lower edge of partition plate 54, and the six reactionchambers 53 a and 53 b communicate via the notches 54 a.

As with partition members 3 and 34 of the above examples, each partitionplate 54 is formed into a thin plate of hydrogen ion-conducting polymerelectrolyte, and the six reaction chambers 53 a and 53 b are arranged sothat reduction reaction chambers 53 a and oxidation reaction chambers 53b are positioned in alternation.

The hydrogen gas lead-out tube 58 is connected to the vapor-phase partof the upper part of the three reduction reaction chambers 53 a, andoxygen gas lead-out tube 57 is connected to the vapor-phase part of theupper part of the three oxidation reaction chambers 53 b. Each partitionplate 54 has the same structure as solar battery module 35 of aboveexample 2, the 21 solar battery modules 55 of the same function aremounted piercingly and in matrix form, the electrolysis cathodes ofthese solar battery modules 55 are exposed to the interior of theelectrolyte of reduction reaction chambers 53 a, and the electrolysisanodes are attached so as to be exposed to the interior of theelectrolyte of oxidation reaction chambers 53 b.

We describe the operation of this photoelectrolytic device 50.

When sunlight is shined onto this photoelectrolytic device 50 from aboveas shown by arrows E with container 51 filled with water as electrolyteto the prescribed level, a photoelectromotive force of 2.0-2.4 V isgenerated in each solar battery module 55, so, as in above example 2,hydrogen gas is produced from the surface of the cathodes in reductionreaction chambers 53 a, and oxygen gas is produced from the surface ofthe anodes in oxidation reaction chambers 53 b. The hydrogen gas issupplied to a hydrogen gas accommodation tank through hydrogen gaslead-out tube 58, and the oxygen gas is supplied to an oxygenaccommodation tank through oxygen gas lead-out tube 57.

In this photoelectrolytic device 50, the cathodes of many solar batterymodules 55 can be arranged in reduction reaction chambers 53 a, and theanodes of many solar battery modules 55 can be arranged in oxidationreaction chambers 53 b, which is suitable for making a large-capacityphotoelectrolytic device. Light reflected by the side surfaces and basesurface of stainless-steel container 51 can be guided into theelectrolyte. Solar battery modules 55 can be removed together withpartition member 54, which is advantageous for doing maintenance, suchas cleaning the solar battery modules 55. The solar battery modules 55themselves of this photoelectrolytic device have roughly the sameoperation and effect as the solar battery modules 10 and 35 of the aboveexamples.

We describe how above examples 1-3 may be partially modified withoutdeparting from the gist of this invention.

1) In spherical solar battery element 11, an n-type silicon singlecrystal and a p+ diffusion layer may be provided instead of p-typesilicon single crystal 15 and n+ diffusion layer 16. Instead of asilicon single crystal as the semiconductor that comprises the sphericalcrystal, one may employ single crystals or polycrystals ofsemiconductors such as germanium (Ge), mixed crystals Si—Ge of siliconand germanium, silicon carbide (SiC), gallium arsenide (GaAs), or indiumphosphorus (InP).

2) The photoelectrolytic devices 1, 30, and 50 are not limited to theabove modes of implementation; the solar battery module andphotoelectrolytic device of this invention may be applied to variousphotoelectrolytic devices that are used for the electrolysis of variouselectrolytes. In this case, the photoelectromotive force of the solarbattery module is appropriately set by appropriately setting the numberof series connections of spherical solar cell elements 11 in accordancewith the required electrolysis voltage.

3) The material from which the electrolysis anodes and cathodes are madeis not limited to what has been referred to above. Pointy tips 13 c, 14c, 46 c, and 48 c formed on the anodes and cathodes are not mandatoryand may be omitted. The material of the catalytic-function coating onthe surface of the anodes and of the catalytic-function coating on thesurface of the cathodes is not limited to what has been referred toabove; one uses a functional material that fits the reaction products.

4) The partition members 3 and 34 and partition plates 54 may be made ofa hydrogen ion-conducting polymer electrolyte other than theaforementioned, or may be made of a positive ion-conducting polymerelectrolyte or negative ion-conducting polymer electrolyte that fits thereaction products. If an opening to allow electrolytic solution to flowthrough (corresponding to opening hole 34 a and notch 54 a) is to beformed in partition members 3 and 34 or partition plates 54, it is notalways necessary that partition members 3 and 34 or partition plates 54be made of an ion-conducting polymer electrolyte in order for the ionsin the electrolytic solution to migrate through this opening to allowthe electrolytic solution to flow through; they may also be made with agas separation material that has the function of separating the gasesproduced by the electrolytic reactions. For example, if hydrogen gas andoxygen gas produced by electrolytic reactions are to be separated, theymay be made with a gas separation material such as polyurethane orpolycarbonate. And because the solar battery module is small and light,partition members 3 and 34 or partition plates 54 do not necessarilyneed to be made in plate form; they may be made with one or more filmshaving gas separation function, and they may be combined with a framemade of metal, synthetic resin, or glass that supports the outsideperimeter of one film and another.

What is claimed is:
 1. A solar battery module for a photoelectrolyticdevice comprising: a cylindrical holding member into which light can beintroduced; said cylindrical holding member has a first end and a secondend; a plurality of solar battery elements contained within saidcylindrical holding member; at least some of said plurality of solarbattery elements are connected with each other; a first electrolysiselectrode; said first electrolysis electrode is electrically connectedto a first outer solar battery element and said first end with a firstseal; said first seal is liquid-tight; a second electrolysis electrode;said second electrolysis electrode is electrically connected to anopposite second outer solar battery element and said second end with asecond seal; said second seal is liquid-tight; and said cylindricalholding member holding said plurality of solar battery elements in acylindrical array which can be illuminated from any radial direction. 2.A solar battery module for a photoelectrolytic device according to claim1, wherein; said solar battery elements are substantially spherical. 3.A solar battery module for a photoelectrolytic device according to claim1, wherein; said solar battery elements are p-type semiconductors.
 4. Asolar battery module for a photoelectrolytic device according to claim1, wherein; said solar battery elements are n-type semiconductors.
 5. Asolar battery module for a photoelectrolytic device according to claim 1wherein; said solar battery elements are polycrystal semiconductors. 6.A solar battery module for a photoelectrolytic device according to claim1, wherein; said solar battery elements include a pn junction.
 7. Asolar battery module for a photoelectrolytic device according to claim1, wherein; said solar battery module is immersed in an electrolyte. 8.A solar battery module for a photoelectrolytic device according to claim1, wherein; a number of said solar battery elements is set according toa desired output voltage and a electrolysis voltage needed for anelectrolyte.
 9. A solar battery module for a photoelectrolytic deviceaccording to claim 1, wherein; at least one of said first electrolysiselectrode and second electrolysis electrode is coated with a catalyticmetal coating to promote electrolysis.
 10. A solar battery module for aphotoelectrolytic device according to claim 1, wherein; at least one ofsaid first electrolysis electrode and second electrolysis electrode hasa pointy tip to reduce overvoltage and to promote electrolysis.
 11. Asolar battery module for a photoelectrolytic device according to claim1, wherein; said solar battery module has a relay conductor interposedbetween at least one of said solar battery element.
 12. Aphotoelectrolytic device comprising: a container into which light can beintroduced; at least one partition member; said at least one partitionmember partitioning said container into at least two distinct fluidisolated areas; a plurality of solar battery modules piercingly attachedto said at least one partition member; said at least one partitionmember has a first surface and a second surface; an electrolytesubstantially filling said container; each of said plurality of solarbattery modules has an anode end and a cathode end; said cathode end isexposed to said electrolyte between said container and said firstsurface; said anode end is exposed to said electrolyte between saidcontainer and said second surface; a first means for circulating saidelectrolyte between said container and said first surface to replenishsaid electrolyte as said electrolyte is electrolyzed; a second means forcirculating said electrolyte between said container and said secondsurface to replenish said electrolyte as said electrolyte iselectrolyzed; a first collecting means for collecting electrolysisproducts created at said anode end; and a second collecting means forcollecting electrolysis products created at said cathode end.
 13. Aphotoelectrolytic device according to claim 12, wherein; each said solarbattery module comprises; a solar battery module for a photoelectrolyticdevice comprising: a cylindrical holding member into which light can beintroduced; said cylindrical holding member has a first end and a secondend; a plurality of solar battery elements contained within saidcylindrical holding member; at least some of said plurality of solarbattery elements are connected with each other; a first electrolysiselectrode; said first electrolysis electrode is electrically connectedto a first outer solar battery element and said first end with a firstseal; said first seal is liquid-tight; a second electrolysis electrode;said second electrolysis electrode is electrically connected to anopposite second outer solar battery element and said second end with asecond seal; said second seal is liquid-tight; and said cylindricalholding member holding said plurality of solar battery elements in acylindrical array which can be illuminated from any radial direction.14. A photoelectrolytic device according to claim 13, wherein; saidsolar battery elements are substantially spherical.
 15. Aphotoelectrolytic device according to claim 13, wherein; said solarbattery elements are p-type semiconductors.
 16. A photoelectrolyticdevice according to claim 13, wherein; said solar battery elements aren-type semiconductors.
 17. A photoelectrolytic device according to claim13, wherein; said solar battery elements include a pn junction.
 18. Aphotoelectrolytic device according to claim 13, wherein; said solarbattery modules are immersed in an electrolyte.
 19. A photoelectrolyticdevice according to claim 13, wherein; a number of said solar batteryelements is set according to a desired output voltage and anelectrolysis voltage needed for an electrolyte.
 20. A photoelectrolyticdevice according to claim 13, wherein; at least one of said firstelectrolysis electrode and second electrolysis electrode is coated witha catalytic metal coating to promote electrolysis.
 21. Aphotoelectrolytic device according to claim 13, wherein; at least one ofsaid first electrolysis electrode and second electrolysis electrode hasa pointy tip to reduce overvoltage and to promote electrolysis.
 22. Aphotoelectrolytic device according to claim 13, wherein; said containerpermits light to enter from at least from above.
 23. A photoelectrolyticdevice according to claim 13, wherein; said partition member is made ofa polymer electrolyte.
 24. A photoelectrolytic device according to claim13, wherein; said polymer electrolyte is a hydrogen ion conductor.
 25. Aphotoelectrolytic device according to claim 13, wherein; said containeris glass.
 26. A photoelectrolytic device according to claim 13, wherein;said at least one partition member is substantially circular; saidplurality of said solar battery modules are radially attached to said atleast one partition member.
 27. A photoelectrolytic device according toclaim 13, wherein; said at least one partition member is a hydrogenion-conducting polymer electrolyte.
 28. A photoelectrolytic deviceaccording to claim 13, wherein; said at least one partition member is apositive ion-conducting polymer electrolyte.
 29. A photoelectrolyticdevice according to claim 13, wherein; said at least one partitionmember is a negative ion-conducting polymer electrolyte.
 30. Aphotoelectrolytic device according to claim 13, wherein; said at leastone partition members are removable.